Electrostatic recording member

ABSTRACT

An electrostatic recording member comprises a recording layer composed of a resin film component and an inorganic pigment or a metal soap dispersed therein, at least one member of the resin film component being selected from the group consisting of fatty acid modified epoxy resin ester, cellulose ester, cellulose ether and chlorinated rubber.

O United States Patent 1191 1111 3,891,787

Ueyama 1 5] June 24, 1975 15 1 ELECTROSTATIC RECORDING MEMBER 3,075,859 1/1963 Relph et a1. 117/175 3,125,458 3/1964 Dalton 117/367 175] Inventor: Osaka Japan 3.247.006 4/1966 Hoge et a1. 117/367 73 Assignee; General Company Ltdq Tokyg' 3,347,702 10/1967 C1ancy 117/201 Japan 3,408,217 10/1968 Obuchl 346/135 3,441,437 4/1969 Epstein et a1.. 117/175 122 Filed: Dec. 3, 1973 3,481,775 12/1969 Albertson 1 117/201 3,639,640 2/1972 Gager 346/135 1 1 pp No: 421,143 3,684,746 3 1972 Juna et a1. 346/135 Related US. Application Data I 163] Continuation of Ser. No. 197.756, Nov. 11. 1971, l e Lesmes abandoned Assistant Exammer-Lorra1ne T. Kendell Attorney, Agent, or Firm-Fitzpatrick, Cella, Harper 52 US. Cl. 428/409; 346/135; 423 323;

[51] Int. Cl B32b 5/16; B41m 5/00 An l trostatic recording member comprises a re- [58] Field of Search 161/182, 162, 184, 268, cording layer composed ofa resin film component and 161/400, 265, 163; 101/401, 128,2, 128,3; an inorganic pigment or a metal soap dispersed 1 17/175, 36.7, 201; 346/135 therein, at least one member of the resin film component being selected from the group consisting of fatty [56] References Cited acid modified epoxy resin ester, cellulose ester, cellu- UNITED STATES PATENTS 1086 ether and chlorinated rubber.

3,025,180 3/1962 Dalton 117/367 7 Claims, 1 Drawing Figure PATENTEIJJUN 24 m5 FIG. I

FIG. 2

ELECTROSTATIC RECORDING MEMBER This is a continuation of application Ser. No. 197.756, filed Nov. 1 l, l97l and now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to an electrostatic recording member. and more particularly to an electrostatic recording member having a recording layer of good inscribability, printability, and seal-affixing property.

2. Description of the Prior Art In general. an electrostatic recording layer should have a surface resistivity higher than IO Q for the purpose of retaining electrostatic latent images. as shown, for example. in Japanese Patent Publication No. 24344/1963. Heretofore, the recording layer of conventional electrostatic member is composed of electrically insulating resin film and therefore, the surface of recording layer has lustre, and low inscribability by pencil. ball pen. and fountain pen, low printability and low seal-affixing property.

This invention relates to an electrostatic recording member free from the disadvantages of the conventional electrostatic recording members.

As resins for forming-a recording layer, heretofore these have been generally used polymers of good charging property such as polyvinylacetate. polyvinylchloride, polyacrylic acid ester, polymethacrylic acid ester and the like. Accessability of recording layer film for ink has been improved by dispersing uniformly inorganic pigment ormetal soap inthe recording layer film to eliminate the surface lustre. However. such a dispersion of pigment in the resin results in lowering the surface resistivity to a value less than 10"!) necessary for electrostatic recording and thereby, good recording is not obtained. v

The present inventor has found that when inorganic pigment or metal soap is dispersed in a film forming resin such as fatty acid modified epoxy resin ester, cellulose ester and chlorinated rubber, the resulting recording lay has a surface resistivity not so lowered by incorporation of the pigment or metal soap. and good recording is'obtained.

SIJMMARY OF THE INVENTION BRIEF DESCRIPTION OFTHE DRAWING FIG. 1 shows schematically an enlarged cross section of an embodiment of electrostatic recording member according to the present invention; and

FIG. 2 shows schematically an enlarged cross section of another embodiment of electrostatic recording member according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an electrostatic recording member composed of two layers, that is, a paper 2 and a recording layer 1 overlying the paper 2. This recording layer is a resin film layer containing at least one of fatty acid modifying epoxy resin ester, cellulose ester, cellulose ether and chlorinated rubber, and an inorganic pigment or a metal soap is disposed therein.

FIG. 2 shows another embodiment of electrostatic recording member of this invention composed of three layers. that is, a support 22, a low resistant layer 23 overlying the support 22, and a recording layer 21 overlying the low resistant layer 23.

It should be noted tht electrostatic recording members according to the present invention are not restricted to those as illustrated above.

Fatty acid modified epoxy resin esters used in this invention may be epoxy resins esterified with a drying oil fatty acid such as tung oil fatty acid, dehydrated castor oil fatty acid, linseed oil fatty acid and the like, a semidrying oil fatty acid such as colza oil fatty acid and the like, or non-drying oil fatty acid such as castor oil fatty acid, cocoa-nut oil fatty acid and the like.

The fatty acid modified epoxy resin have preferably a degree of esterification ranging from 30 to Representative fatty acid modified epoxy resins are Beckosol P 786, 787, and 789 (trade names. supplied by Japan Reichhold Co. Ltd., they are castor oil fatty acid ester, cocoa-nut oil fatty acid ester, and linseed oil fatty acid ester, respectively).

Cellulose ester is a cellulose which hydroxy groups are esterified with a mineral acid such as nitric acid, sulfuric acid, and the like, or a fatty acid such as acetic acid. propionic acid, butyric acid and the like.

Represent cellulose esters are nitrocotton (supplied by Asahi Kasei, nitric acid ester), acetate cotton (supplied by Dainihon Celluloid. acetic acid ester), and Half-Second Butyrate Type EAB-38l (supplied by Eastman Chemical Products INC.. acetic acid and butyric acid ester).

Cellulose ether is cellulose which hydroxy group is etherified. Representative cellulose ethers are alkyl ether such as methyl ether, ethyl ether and the like. aralkyl ether such as benzyl ether and the like. For example, there may be mentioned Metorose (trade name, supplied by Shinetsu Kagaku, methyl ether) and Ethocel (trade name. supplied by Dow Chemical Co.).

Chlorinated rubber is chlorinated natural rubber. For example, there may be mentioned Adeka Chlorinated Rubber (trade name, supplied by Asahi Denka Kogyo).

Representative inorganic pigments dispersed in the resin film are calcium carbonate, clay, titanium oxide, and mica. Representative metal soaps are barium stearate, calcium stearate, barium palmitate, and calcium palmitate. These examples of pigment are white pigments, but these may be used color pigments other than white pigment.

The results of experiment are shown in Table l.

TABLE I Tradc name (Supplier) Film forming resin Surface resistivity of recording layer (ohm) (l) Polyvinylchloride Denka Vinyl 1000A 7 X It)" (Denki Kagaku Kogyo) (2) Polymethylmethacrylatc Acrynul No. 40 X H)" (Toei Kasei) (3) Polyvinylacctate Gosenyl T50 85 X lO' (Nihon Gosei) (4) Polystyrene Dialex 6 X (Mitsubishi Monsanto) (5) Phenolic resin Tamanol 1000 S 1.] X [0" (Arakawu Rinsan) (6) Dehydrated castor Beckosol P 786-50 1.2 X 10' oil epxoy resin ester (Japan Reichhold) (7) Nitrocellulose Nitrocotton H /4 2 x It) (Asahi Kasei) (8) Cellulose acetate Half-Second Butyrate 4 X H) EAB 381 (Eastman Chemical) (9) Ethyl cellulose Ethocel STP 4.6 X l()"- (Dow Chemical) IU) Rubber chloride Adeka Rubber Chloride 2.6 X 10 No. 2 (Asahi Denka) Note:

( l Pigment employed as titanium oxide of rutile type.

(2) Thickness of coating of recording layer as about 5 microns, I3) The ratio of resin to pigment as lzl.

(4) The support as a base papcr subjected to a resistance-lowering treatment as shown in Example I. (5) Electric resistance was measured by a dynamic condenser clcctromctcr (supplied h Toshiba).

(6) Measurement was effected at C at 6064 R.H,

As pigment. titanium oxide of rutile type was employed, and the ratio of resin to pigment was lzl. The experiment was made with respect to various resins, in Table l, (l) polyvinylchloride, (2) polymethylmethacrylate and (3) polyvinylacetate have been generally used for electrostatic recording, but when pigment is dispersed in any of them, surface resistivity of the resulting recording layer is reduced to a great extent and becomes that of less than 10 (4) Polystyrene and (5) phenolic resin have large volume resistivity and they are l0 IO Qcm and I0' IO Q-cm, respectively. However, surface resistivity of layer of such resins in which pigment is dispersed is less than IO' Q.

On the other hand, (6) dehydrated castor oil epoxy resin ester (fatty acid modified epoxy resin ester), (7) nitrocellulose. (8) cellulose acetate and butyrate (cellulose ester), (9) ethyl cellulose (cellulose ether) and (10) chlorinated rubber can retain fairly high resistance even when pigment is dispersed in a film of said resin and the surface resistivity is higher than IO' Q.

There is not yet fully understood the mechanism enabling to prevent lowering surface resistivity and retain substantially high resistance (surface resistivity higher than 10 12) when pigment or metal soap is dispersed in a film of fatty acid modified epoxy resin, cellulose ester, cellulose ether or chlorinated rubber, but it is considered that adhesion between such resin and pigment or metal soap is good and thereby the surface of pigment is appropriately covered with the resin.

Amount of pigment or metal soap to be dispersed in the resin film as mentioned above may be appropriately selected. The ratio of pigment or metal soap to resin is preferably higher than 1:5. lnscribability, seal-affixing property and printability are remarkably improved and surface lustre is reduced to a great extent in the abovementioned ratio range. However, when the amount of pigment is too much, there occur fog upon electrostatic recording, choking of writing instruments and peeling of recording layer. Therefore, most preferable ratio of pigment or metal soap to resin ranges from 1/1 to 1/5. When a fatty acid modified epoxy resin ester, cellulose ester, cellulose ether, or chlorinated rubber as employed in this invention is mixed with polyvinylchloride, acrylic acid ester or methacrylic acid ester used in conventional electrostatic recording and pigment or metal soap is dispersed and the resulting mixture is made into a film for recording layer, the recording layer has sufficiently high surface resistivity to give good recording and inscribability is improved to a great extent. These advantages can be sufficiently obtained when the amount of resin as used in this invention such as fatty acid modified epoxy resin ester and the like is at least 30% by weight on the basis of total amount of the resin mixture.

The following examples are given for illustrating the present invention, but should not construed as limiting the present invention. Parts in the following examples are by weight unless otherwise specified.

EXAMPLE 1 (Reference Example) To a base paper of about 60 p. thick subjected to a resistance-lowering treatment and having surface resistivity of 10" Q was applied the following formulation an dried to form a recording layer of about 5 u thick.

Titanium oxide of mtile type R820 l0 parts (trade name. supplied by lshihara Sangyo) Denka Vinyl 1000A l0 parts (trade name. supplied by Denki Kagaku Kogyo) Toluene 40 parts MEK 40 parts Surface resistivity of the resulting recording layer was 5 X 10' (I and any good recording was not obtained.

EXAMPLE 2 (Reference Example) The procedure of Example 1 was repeated except that the following formulation was used in place of that of Example 1.

Calcium carbonate 15 parts Acrynal No. (trade name. supplied by 35 parts Toei Kasei, polymethylmethacrylate) Toluene [00 parts Surface resistivity of the resulting recording layer was 5 X l fl and any good recording was not obtained.

EXAMPLE 3 The procedure of Example 1 was repeated except that the following formulation was employed in place of that of Example 1.

Calcium carbonate 40 parts Beckosol P 786-50 (trade name. supplied by 60 parts Japan Reichhold K.K.. 50% solution of dehydratedcastor oil epoxy ester in xylene) Toluene 60 parts Cobalt naphthenate 0.5 parts Surface resistivity of the recording layer was l X l0 l) and good recording wasobtained.

EXAMPLE 4 The procedure of Example I wasfollowed except that the following formulation was used in place of that of Example I. i

Titanium oxide of rutile type R 820 20 parts Beckosol P 786-50 40 parts Toluene 40 parts Cobalt naphthcnate 0.5 parts EXAMPLE 5 Following the procedure of Example 1, the formulation as shown below was applied.

Lake Red RC (trade name. supplied 2 parts by Dainihon Ink Co.)

Titanium oxide of rutile type. R 820 5 parts Beckosol P 786-50 20 parts Toluene 30 pans Cobalt naphthenate 0.5 parts Surface resistivity of the resulting recording layer was 3 X I! and good recording was obtained, in this case the recording paper was red.

EXAMPLE 6 The procedure of Example 1 was repeated by using the following formulation in place of that of Example l.

Barium stearate l0 parts Beckosol P 786-50 parts Toluene 50 parts Cobalt naphthenate 0.5 parts Surface resistivity of the resulting recording layer was 4 X 10" (2 and good recording was obtained.

EXAMPLE 7 The procedure of Example I was repeated except that the following formulation was used in place of that in Example 1.

Titanium oxide of rutile type. R820 10 parts Half-second Butyrate (supplied by Eastman 10 parts Chemical Products. cellulose acetate and butyrate) Ethyl acetate 50 parts Surface resistivity of the resulting recording layer was 4 X 10' (1 and good recording was obtained.

EXAMPLE 8 The procedure of Example 1 was repeated except that the following formulation was employed in place of that in Example 1.

Titanium oxide of rutile type R820 20 parts Ethocel STP (trade name. supplied by 20 parts Dow Chemical. ethyl cellulose) Methanol 60 parts Surface resistivity of the recording layer was 4.6 X [0' l and good recording was obtained.

EXAMPLE 9 The procedure of Example 1 was repeated except that the following formulation was employed.

Titanium oxide of rutile type. R820 20 parts Adeka Chlorinated Rubber No. 2 (trade name. 20 parts supplied by Asahi Denki) Toluene 60 parts Surface resistivity of the recording layer was 2.6 X 10 ll and good recording was obtained.

EXAMPLE ID The procedure of Example I was repeated except that the following formulation was used in place of that in Example 1.

Titanium oxide of rutile type. R820 50 parts Beckosol P 786-50 15 parts Acrynal No. (trade name. supplied by Toei 35 parts Kasei. Methyl methacrylate) Toluene [50 parts Cobalt naphthenate 0.5 parts Surface resistivity of the recording layer was 4 X 10" (l and good recording was obtained.

EXAMPLE I l The procedure of Example I was repeated except that the following formulation was employed in place of that in Example 1.

Calcium carbonate 8 parts Beckosol P 786-50 l5 pans Acrynal No. 80 12 parts Toluene 25 parts Cobalt naphthenate (L5 parts Surface resistivity of the recording layer was 7.0 X l Q and good recording was obtained.

According to the present invention. an electrostatic recording member of good inscribability, printability and seal-affixing property is obtained without deteriorating the recording characteristics. When the support is paper, the resulting electrostatic recording paper is almost the same as usual paper with respect to appearance. inscribability, printability and seal-affixing property.

I claim:

1. An electrostatic recording member which comprises an electrically low resistant substrate having a recording layer thereon which consists essentially of an inorganic pigment or a metal soap dispersed in a resin film which is composed of at least 30% by weight, based on the weight of the resin film, of a fatty acid modified epoxy resin ester having a degree of esterifcation of from 30% to 90% and up to 70% by weight of a member selected from the group consisting of polyvinyl chloride and polymers of acrylic acid esters and methacrylic acid esters, wherein the surface resistivity of the recording layer is at least about l0 ohm-cm.

2. An electrostatic recording member according to claim 1 in which the inorganic pigment is selected from the group consisting of calcium carbonate, clay, titanium oxide and mica.

3. An electrostatic recording member according to claim 1 in which the metal soap is selected from the group consisting of barium stearate, calcium stearate. barium palmitate. and calcium palmitate.

4. An electrostatic recording member according to claim 1 in which the fatty acid modified epoxy resin ester is selected from the group consisting of epoxy resins esterified with a drying oil fatty acid, semidrying oil fatty acid or non-drying oil fatty acid.

5. An electrostatic recording member according to claim 1, in which the weight ratio of the inorganic pigment or the metal soap to the resin film is about hi to 1:5.

6. An electrostatic recording member according to claim 1, in which the surface resistivity of the electrically low resistent substrate is less than about 10 ohm.

7. An electrostatic recording member according to claim 1, wherein said resin film is composed entirely of said fatty acid modified epoxy resin ester.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 891,787 Dated June 24, 1975 Inventor-(s) SEIZI UEYAMA It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Col. 2, line 7, after "recording layer" insert -l-;

line 17, "tht" should be that-;

Col. 3, line 52, after "resin" insert ester;

Col. 4, line 49, "an" should be and;

Claim 1, Col. 8, line 3, ohm-cm." should be -ohms--;

Claim 6, Col. 8, lines 22 and 23, "ohm.cm." should be ohms-;

Signed and Scaled this twenty-se h D3) Of January 1976 [SEAL] Arrest:

C. MARSHALL DANN A nesting Officer 

1. AN ELECTROSTATIC RECORDING MEMBER WHICH COMPRISES AN ELECTRICALLY LOW RESISTANT SUBSTRATE HAVING A RECORDING LAYER THEREON WHICH CONSISTS ESSENTIALY OF AN INORGANIC PIGMENT OR A METAL SOAP DISPERSED IN A RESIN FILM WHICH IS COMPOSED OF AT LEAST 30% BY WEIGHT, BASED ON THE WEIGHT OF THE RESIN FILM, OF A FATTY ACID MODIFIED EPOXY RESIN ESTER HAVING A DEGREE OF
 2. An electrostatic recording member according to claim 1 in which the inorganic pigment is selected from the group consisting of calcium carbonate, clay, titanium oxide and mica.
 3. An electrostatic recording member according to claim 1 in which the metal soap is selected from the group consisting of barium stearate, calcium stearate, barium palmitate, and calcium palmitate.
 4. An electrostatic recording member according to claim 1 in which the fatty acid modified epoxy resin ester is selected from the group consisting of epoxy resins esterified with a drying oil fatty acid, semidrying oil fatty acid or non-drying oil fatty acid.
 5. An electrostatic recording member according to claim 1, in which the weight ratio of the inorganic pigment or the metal soap to the resin film iS about 1:1 to 1:5.
 6. An electrostatic recording member according to claim 1, in which the surface resistivity of the electrically low resistent substrate is less than about 109 ohm. cm.
 7. An electrostatic recording member according to claim 1, wherein said resin film is composed entirely of said fatty acid modified epoxy resin ester. 